I2C power monitor

[Vu Nguyen]

Hi,

I'm new to I2C and am hoping someone/anyone could point me in the
right direction.

I'm trying to find or build something that would allow my linux box to
test an AC power source. The power source is just the AC power jack
on the wall.

I've found solutions to testing power supplies, but I haven't found
anyway to test what the power supply plugs into (the wall AC jack).

If anyone could help me out, I'd be very grateful.

Thanks.

[simon]

You don't really say what you are trying to do here. first suggestion,
if you are interested in power quality, is just get an APC UPS with
the serial port, and that way you get a UPS and power monitor.

If you want to use I2C, say if this is just part of a more ambitious
instrumentation project, then look at this PC (usb&rs232) to I2C
adaptor.

www.i2cchip.com

It runs under linux, or over telnet etc. That gives you an easy ascii
interface to the I2C.
It also has provision for full galvanic isolation. This is pretty
handy for monitoring the mains, actually for any instrumentation,
since PC's do ugly things to thier ground wire.

If you want to monitor voltage, use a little power transformer and any
i2c a-d chip off a rectifier.

If you want to monitor current, get a CT (current transformer). This
will give you an isolated sample of the current at some ratio eg
1/100th. rectify this and put into an A-D

If you are interested in true power, then either:
a) get a magnetostrictive bridge chip eg philips kmz10. Feed the top
of the bridge through a resistor with the mains voltage (directly or
via a transformer) and wrap the current sense wire around it. Average
the voltage. This does a direct instantaeneous multiply
b) use a power meter chip eg from SAMES and use a pcf8593 as a counter

If you want to monitor frequency get 2 of the philips i2c clock chips
8593. Use one with a 32768 crystal, and the other counting the mains
cycles. Now you can calc the frequency.

use...@vuter.com (Vu Nguyen) wrote in message news:<1d99dd8b.02091...@posting.google.com>...

[N. Thornton]

use...@vuter.com (Vu Nguyen) wrote in message news:<1d99dd8b.02091...@posting.google.com>...

I guess you'll need a transformer plus an A to D. A small transformer
will reduce your mains voltage down to something sensible, and isolate
it, which is important. Then you can feed that into whatever A to D
the PC has, like the sound card for instance. For the sound card
you'll only want a fraction of a volt, so use 2 resistors on the TF
output to cut the V down further.

Mains can kill, make sure you know what youre doing or dont do it,
etc.

Regards, NT